The conventional power supply device with power redundant mechanism may generate a main direct current (DC) power and a redundant DC power at the same time during the operation. Generally, both of the main DC power and the redundant DC power are provided to the external device when the main DC power is normal. On the contrary, the redundant DC power is provided to the external device when the main DC power is abnormal. Therefore, the power supply device can maintain the power supply function even if the main DC power has abnormalities.
However, when the conventional power supply device with power redundant mechanism is operated in a cold redundant (CR) mode, the input power consumption is about 10 W, which is relatively high.